Auxiliary sighting device for grenade launching firearms



Jan, 119, 1965 R. F. MAGARDO 3,165,836

AUXILIARY SIGHTING DEVICE FOR GRENADE LAUNCHING FIREARMS Filed Oct. 12, 1962 2 Sheets-Sheet l INVENTQR. Huber F. Mggtmflu 1.}. PJJA 65192,-

United States Patent filice 3 ,lfi ,83fi Patented Jan. 19, 1965 Fran 3,165,836 SEGHTING DEVECE FGR GRENAEE LAUNLIHING FIREARMS Robert F. Magardo, Springfield, Mass assignor to the "United fitates of America as represented by the Secretary of the Army Filed Get. 12, 1962, Ser. No. 230,333 7 Ciainis. ((Il. 33--47) (Granted under 'llitie 35, ELS. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to sights for firearms and more particularly to auxiliary sights which are used with launcher attachments thereon.

It is one object of this invention to provide for use with a launcher attachment to a firearm an auxiliary sighting device which progressively moves the sight line outwardly away from the firearm as the elevation angle thereof is increased so that the sight line will not be blocked by the launcher attachment or the supporting hand thereon.

It is another object of this invention to provide such a sighting device in which the known component of drift of the launched projectile is automatically compensated for as the elevational angle of the firearm is increased.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is an elevational view of a rifle with the sighting device of this invention mounted thereon;

FIG. 2 is an enlarged partially cross-sectioned elevational view of the sighting device;

FIG. 3 is an end View of the sighting device looking forwardly from the butt end of the rifle;

FIG. 4 is a View taken along line 44 of FIG. 2;

FIG. 5 is a schematic view showing the corelationship between the axes of the front and rear sights and the path,

treated two-dimensionally, in which the pivotal points of the front and rear sights move during the elevational displacement of the sighting device and the parallel alignment of the sight lines at the different range settings when the sighting device is not corrected for drift; and

FIG. 6 is a schematic view showing exaggerated the relationship of the sight line with the bore axis of the firearm as the drift of the projectile is automatically compensated for at different range settings of the sighting device.

Shown in the figures is a firearm 12 to the barrel of which there is mounted a launcher 14 which depends from the barrel and may be gripped by one hand of a shooter for operational purposes and for aiming the launcher at a target 16, Launcher l4 propels a projectile 15 which is of a high trajectory type, such as is used with the M79 Grenade Launcher, so that firearm 12 has to be elevated to a high angle when target 16 is some distance away, whereby the conventional sights of the firearm are inoperative. Launcher 14 is conventionally rifled to spin projectile 15 during its flight and, because the projectile is of relatively large caliber and is propelled with a relatively low velocity, the spin causes the projectile to drift in the direction in which the riding twists which, in this case, is towards the right.

Mounted on the left side of firearm 12, for use by a right-handed shooter, is a sighting device 18 which is arranged, as hereinafter described, to progressively move the sight line, noted at YY, away from the adjacent side of firearm 12, as the elevation of the firearm is increased, so that the sight line will not be blocked by launcher 14 or a hand grasping the launcher. Sighting device 18 also is arranged, as hereinafter described, to automatically compensate for the known component of drift of projectile to the right.

Sighting device 18 includes a housing 20 having a ring casing 22 with a cylindrical opening 24 arranged transversely or" the p'incipal axis of the housing and a pair of tube-stubs 26 which extend oppositely and in coaxial alignment from the periphery of the ring casing. Tubestubs 2d are each provided with an axial bore 28 which has communication with opening 24. Opening 24 receives a ring 30 the outside diameter of which is substantially the same as the inside diameter of ring casing 22 so that the housing is rotatably related thereto. An arcuate gear sector 32 is formed around a 95 section of the periphery of ring 30. The remaining periphery of ring 30 provides a bearing surface for rotation of housing 2i) relative to the ring. Fastened to the inner edge of ring 30 is a circular plate 34 having a diameter similar to the inside diameter of ring casing 22 to provide a cover for the inside end of opening 24. Plate 34 is attached to firearm 12 by a screw 36 which extends through the side of the receiver of firearm 12 so that the plate is immovable relative thereto and so that housing 24) is rotatable in a plane which is parallel with the vertical plane of firearm 12 noted at O() in FIG. 3. Sighting device 18 may be mounted on either side of firearm l2 and is indexed relative thereto by means of a pin 37 which extends from plate 34 for engagement with a mounting hole 39 in each side of the firearm receiver.

Gear sector 32 is meshingly engaged by a pinion gear 38 which is mounted on an axle 40 which is journaled in housing 20 parallel to the central axis of ring 30. A knob %2 is connected to the outside end of axle 40 by means of a clutch device 4 which is controlled by a screw 46. When screw 46 is tightened, knob 42 is connected directly to axle 40 so that rotation of the knob causes rotation of the pinion gear 38 relative to ring 30. As ring 30 is fixed relative to firearm 12, through plate 34, rotation of knob 42 causes angular displacement of sighting device 18 around the axis of ring 30. Pinion gear 38 is related to gear sector 32 at a six to one ratio so that a six degree rotation of knob 42 changes the elevation of sighting device 18 one degree. When screw 46 is loosened, knob 42 may be turned relative to axle 4-0 so that sight device 18 may be zeroed relative to launcher 14 as here inafter explained. Provided around the periphery of knob 42 are range markings 48 which are indexed by a reference line 50 on ring casing 22 and are spaced according to predetermined calculations so that sight device 18 is calibrated for selected ranges. Plunger and detent means 5'2 secures knob 42 in the selected range position identified by range markings 48 and reference line 50. Range markings 48 extend oppositely and similarly from the 0 marking, as shown in FIG. 3, to provide for right and left hand installation on firearm 12 as hereinafter described.

A shaft 54 extends through bores 28 with the ends of the shaft extending respectively from the ends of the tubestubs 26. A pair of slots 56 in ring 30 permit extension of shaft 54 therethrough and the uninterrupted rotation of the ring for 95 relative to the shaft. Mounted on the front end of shaft 54 is a front sight 58 and a rear sight 60 is mounted to the rear end of the shaft so that the long axis of the front sight, noted at A-A, and the long axis of the rear sight, noted at 13-3, are in a plane which coincides with the long axis of the shaft and so that the front and rear sights are equidistant from the axis of ring 3i). Mounted on shaft 54 within opening 24 is a pinion gear 62 which has meshing engagement with an arcuate rack 64 fixed to the inside of plate 34 so that elevational displacement of sight device 18 around the axis of ring 30 causes rotation of the shaft and, consequently, pivoted that is, when sight device 18 is rotated 1 around the axis of ring 30, front sight 58 and rear sight 68 are pivoted 2 around the axis of shaft 54. Rack 64 extends in a 95 arc so as to provide for installation of sighting device 18 on either side of firearm 12 as hereinafter described.

Front sight 58 and rear sight 60 are each composed of two pieces which are pivotally connected, as shown in FIGS. 2 and 3, so that they may be folded inwardly towards each other and out of the way when not in use. Rear sight 60 is terminated at the free end by an aperture 66 and front sight 58 includes bead 68 which is carried at the end of a rod 70. Rod 70 is slidingly received by a well 72 which extends longitudinally into front sight 58 from the free end thereof and the rod is provided with a pair of notches including a first notch 74 and a second notch 76 spaced therefrom closer to head 68. A setscrew 78 is threadingly mounted in front sight 58 at right angles to rod 70 and so as to be engageable with one of the notches 74 and 76. First notch 74 is so located in rod 70 that, when engaged by setscrew 78, the center of bead 68 is spaced a predetermined distance farther from the axis of shaft 54 than is the center of aperture 66 and, when second notch 76 is engaged by the setscrew, the center of the bead is spaced the same predetermined distance closer to the axis of shaft 54 than is the center of aperture 66.

The aforementioned predetermined distance is calculated so that the drift of projectile 15 propelled from launcher 14 is automatically compensated for at the different settings of range settings 48 as hereinafter described. When bead 68 is positioned by engagement of setscrew 78 with first notch 74, the drift is compensated for when sighting device 18 is mounted on the right side of firearm 12 and the drift is to the right. When sighting device 18 is mounted on the left side of firearm 12, bead 68 is moved in to where second notch 76 is engaged by setscrew 78 for compensation of the drift.

The operation of sighting device 18 can best be understood by referring to FIG. wherein M is the point of junction of front sight axis AA, extending through the center of bead 68, with the axis of shaft 54, N is the point of junction of rear sight axis B-B, extended through the center of aperture 66, with the axis of the shaft and P.P is the path, treated two dimensionally, through which points M and N travel when the sight device is rotated around the central axis of ring 30, noted at W. Bead 68 travels in a parabola shown two-dimensionally at F in FIG 5 and aperture 66 travels in a parabola shown two-dimensionally at R in the same figure because, when sight device 18 is rotated around axis W of ring 30, front sight 58 and rear sight 60 are simultaneously rotated around the axis of shaft 54. As is shown schematically in FIG. 5, when the distance from the center of bead 68 to point N is the same as the distance from the center of aperture 66 to point M, sight line YY is parallel to the plane of path P-P at all range settings of knob 42. However, when setscrew 78 is in engagement with first notch 74 or second notch 76, depending upon which side of firearm 12 sight device 18 is mounted, the radius of the arc in which the center of head 68 swings is respectively longer or shorter than the predetermined distance of the radius of the arc in which the center of aperture 66 swings to compensate for the known component of drift as hereinafter noted.

Sight device 18 is zeroed, respective to launcher 14, after setscrew 78 is engaged with the proper one of the notches 74 or 76, by turning knob 42 to where sight line YY is parallel with bore axis X-X of launcher 14. Then, screw 46 of clutch device 44 is loosened and knob 42 is '4 turned to where the 0 setting of range markings 48 coincides with reference line 50 on ring casing 22. Screw 46 is then tightened.

VJhen front sight 58 and rear sight 60 are swung out- Wardly as housing 20 is rotated for increase in range settings, bead 68 lags behind aperture 66 when second notch 76 is engaged by setscrew 78 and, therefore, as shown in FIG. 6, the angular relationship between sight line YY and bore axis XX is increased as the range setting is increased. When first notch 74 is engaged by setscrew 78, bead 68 leads aperture 66 so that the angular relationship between sight line YY and bore axis XX is similarly increased, with an increase in range settings, but the sight line is directed to the right of bore axis X-X for right hand mounting on firearm 12. The degree of drift is exaggerated in FIG. 6 because the known component of drift of projectile 15 is 0 8.6 at meters, 0 17.25 at 200 meters, 033.7 at 300 meters and 15.5 at 375 meters. These progressively increasing degrees of drift can be approximated by locating first notch 74 so that, when engaged by setscrew 78, the distance of the center bead 68 from the axis of shaft 54 is .080 inch longer than the distance between the center of aperture 66 to such axis, and second notch 76 is located so that, when engaged by the setscrew, the distance between the center of the bead and the shaft axis is .080 inch shorter than the distance between the center of the aperture and such axis.

To transfer sighting device 18 from the left to the right side of firearm 12 for a left-handed shooter, screw 36 is removed, which frees the sight device, atnd then the sight device is remounted on the opposite side of the firearm. Front sight 58 and rear sight 60 are rotated around the axis of shaft 54 so that the opposite end of rack 64 is engaged with pinion gear 62 and the opposite set of range markings 48 become upright when housing 28 is turned over for mounting on the opposite side of firearm 12. Setscrew 78 is then unloosened and head 68 is pulled outwardly until first notch 74 is positioned for engagement by the setscrew and retightened. Sighting device 18 is then zeroed as hereinbefore described.

From the foregoing it is clearly apparent that there is provided herein an auxiliary sighting device which is especially well adapted for use with launcher attachments on firearms as the sight line does not become blocked by the launcher or the supporting hand thereon as the elevation of the firearm is increased and because the drift of the projectile is automatically compensated for by very simple means.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. A sighting device for a firearm adapted for pro pelling a high trajectory projectile having a known com ponent of drift, the sighting device including a housing, a ring with a central axis mounted in said housing for relative rotation, means for fixedly attaching said ring to the firearm so that said housing is rotatable around the axis of said ring in a plane parallel to a vertical plane of a firearm, a knob with calibrated range markings mounted for rotation on said housing, means for linking said knob to said ring so that rotation of said knob is converted to rotation of said housing, a front sight, a rear sight, means for mounting said front and rear sights on said housing for pivotal displacement respective thereto around an axis disposed transversally to the axis of said ring, and means for converting rotation of said housing to pivotal displacement of said front and rear sights so that a sight line established therealong is progressively moved away from the firearm as said housing is rotated to elevate the sight line relative to the firearm.

2. The sighting device as defined in claim 1 and in luding means for automatically compensating for the known component of drift as said knob is rotated to a. selected range marking.

3. The sighting device as defined in claim 1 wherein said means for mounting said front and rear sights includes a shaft journaled in said housing transversally to the axis of said ring, and wherein said means for converting rotation of said housing to pivotal displacement of said front and rear sights includes a pinion gear mounted on said shaft and an arch-ate rack carried by said ring so as to have meshing engagement with said pinion gear.

4. The sighting device as defined in claim 3 wherein said front sight is provided with means for automatically compensating for the known component of drift as said knob is rotated to its selected range marking.

5. The sighting device as defined in claim 4- wherein said front and rear sights are pivotal 180 to the opposite limits of their pivotal displacement when said sighting device is installed on the opposite side of the firearm and said range markings include two similar range settings extending in opposite directions from a zero setting with each of said range settings corresponding to one of the two installed positions of the sighting device h on the firearm, and wherein said means for compensating for the known component of drift includes a bead adjustable to one of two positions along the longitudinal line of said front sight.

6. The sighting device as defined in claim 4 wherein said rear sight is provided with an aperture and wherein said drift compensating means of said front sight includes a bead and means for adjusting the position thereof so that the center of said head is displaceable in an are having a radius the length of which differs a predetermined distance from the arc in which the center of said aperture is moved as said front and rear sights are pivoted, to compensate for the known component of drift.

7. The sighting device as defined in claim 6 wherein said means for linking said knob to said ring includes a clutch device to permit free rotation of said knob to the zero setting of said range marking after said sight device is zeroed respective to the firearm.

No references cited.

ISAAC LISANN, Primary Examiner. 

1. A SIGHTING DEVICE FOR A FIREARM ADAPTED FOR PROPELLING A HIGH TRAJECTILE HAVING A KNOWN COMPONENT OF DRIFT, THE SIGHTING DEVICE INCLUDING A HOUSING A RING WITH A CENTRAL AXIS MOUNTED IN SAID HOUSING FOR RELATIVE ROTATION, MEANS FOR FIXEDLY ATTACHING SAID RING TO THE FIREARM SO THAT SAID HOUSING IS ROTATABLE AROUND THE AXIS OF SAID RING IN A PLANE PARALLEL TO A VERTICA PLANE OF A FIREARM, A KNOB WITH CALIBRATED RANGE MARKINGS MOUNTED FOR ROTATION OF SAID HOUSING, MEANS FOR LINKING SAID KNOB TO SAID RING SO THAT ROTATION OF SAID KNOB IS CONVERTED TO ROTATION OF SAID HOUSING, A FRONT SIGHT, A REAR SIGHT, MEANS FOR MOUNTING SAID FRONT AND REAR SIGHTS ON SAID HOUSING FOR PIVOTAL DISPLACEMENT RESPECTIVE THERETO AROUND AN AXIS DISPOSED TRANSVERSALLY TO THE AXIS OF SAID RING, AND MEANS FOR CONVERTING ROTATION OF SAID HOUSING TO PIVOTAL DISPLACEMENT OF SAID FRONT AND REAR SIGHTS SO THAT A SIGHT LINE ESTABLISHED THEREALONG IS PROGRESSIVELY MOVED AWAY FROM THE FIREARM AS SAID HOUSING IS ROTATED TO ELEVATE THE SIGHT LINE RELATIVELY TO THE FIREARM. 